Salt, baking soda, glucose....

If someone would be so kind to help...
I was just wondering about the effects of sodium chloride, sodium bicarbonate, and glucose on the human brain.
I was wondering what the "toxic limits", so to speak, would be- and if the effects of large amounts of these chemicals were easily reversed. How long would it take for these chemicals to actually seep into the brain? Or does that even happen?
I know that the effects of glucose can be pretty quick, as my mother is a diabetic- but these effects can be reversed quickly as well. But what happens to the brain when much higher levels of glucose are introduced?
MSDS sheets were of no help, as they make all chemicals sound dangerous and are not really meant to be used in a medical capacity.
(Honestly most interested in what happens to the brain, not so much with what happens to the rest of the body unless it's in direct relation.. Just in case anyone thought I was posting in the wrong area)